ROLE OF DENSITY-FLUCTUATIONS IN THE SOLVATION STRUCTURE IN SUPERCRITICAL DILUTE-SOLUTIONS - A MOLECULAR-DYNAMICS STUDY

Molecular dynamics and Gibbs ensemble Monte Carlo simulations have bee n used to investigate solvation structures in a dilute supercritical s olution of two particle types interacting via Lennard-Jones potentials , Spatial correlations evidenced in the solute-solvent radial distribu tion functions near the critical point are found to depend strongly on the simulation cell size, There are significant differences between t he solvent-solvent and solute-solvent radial distribution functions in the liquid and supercritical states. The mechanism of the development of a dynamic solvation structure around the solute is revealed in the density fluctuations in the critical region. In the liquid state ther mal motion prevents strong pair correlations from appearing, masking u nderlying differences in the solvent-solvent and solute-solvent intera ction potentials.